DOT Inspection methods

hey TRusers, I have a quick question regarding the method DOT Inspectors use to check for air leaks. I have read somewhere that a vehicle that leaks more than 4psi per minute is subject to out of service, but I cant seem to find any citation.

But here's an encounter I heard on the airwaves today, DOT Pulled over a truck for inspection and the kid was using soap and water to check for air leaks. So My two concerns over this method are; isn't an air leak audible not visible?, and wouldn't the water create rust on delicate brake components like foot valves and relay valves? Is there a way to refuse the inspector from using soap and water?

hey TRusers, I have a quick question regarding the method DOT Inspectors use to check for air leaks. I have read somewhere that a vehicle that leaks more than 4psi per minute is subject to out of service, but I cant seem to find any citation.

Pay attention the next time you are inspected. The applied pressure test is a leak test, lose 4 psi or more in 1 minute, you failed. The same test that is done during DMV testing for a CDL.

Pay attention the next time you are inspected. The applied pressure test is a leak test, lose 4 psi or more in 1 minute, you failed. The same test that is done during DMV testing for a CDL.

Actually the OOS criteria is somewhat different than the CDL test.

k. Air Loss Rate
If an air leak is discovered and either the primary or secondary reservoir pressure is not maintained when: (396.3(a)(1))
(1) Governor is cut-in;
(2) Reservoir pressure is between 80 – 90 psi (551 – 620 kPa);
(3) Engine is at idle; and,
(4) Service brakes are fully applied.

and wouldn't the water create rust on delicate brake components like foot valves and relay valves? ?

The exterior of the valves are not that delicate, most made of aluminum and no soapy water can enter the valves (If there is a leak the escaping air prevents entry and if there is no leak it can't enter either. Most valves are exposed to the elements anyhow.

Originally Posted by thesvg

Is there a way to refuse the inspector from using soap and water?

If an officer or anyone els suggests using soapy water to help find a leak that you cannot otherwise find, why would anyone object?

k. Air Loss RateIf an air leak is discovered and either the primary or secondary reservoir pressure is not maintained when: (396.3(a)(1))(1) Governor is cut-in;(2) Reservoir pressure is between 80 – 90 psi (551 – 620 kPa);(3) Engine is at idle; and,(4) Service brakes are fully applied.

Best regards

That is the procedure we use to determine if an air loss, any air loss anywhere in the system, if the vehicle should be placed out of service.

Another air loss item that can place a vehicle out of service is an audible air leak in a brake hose that is at a place in the hose other than at a proper connection. This refers to AUDIBLE air leaks, no soap required.